Alder sawfly

The Alder sawfly (Eriocampa ovata) is an insect belonging to the order Hymenoptera and the family Tenthredinidae. It is widely recognized as a specialized pest that targets various alder species, causing significant damage to foliage in both forest environments and managed landscapes.

The primary host plants for this pest include trees of the genus Alnus. Adult sawflies lay their eggs into the leaf tissue, ensuring that larvae have immediate access to nutrients upon hatching. The presence of the pest is often identified by the distinct feeding habits of the larvae, which are typically active during the summer months.

The biology of Eriocampa ovata typically involves one or two generations per year depending on environmental temperature and moisture levels. The pest overwinters as pupae inside robust cocoons embedded in the soil. Once temperatures rise in the spring, adults emerge, mate, and begin the cycle of egg-laying on host leaves.

Damage caused by the larvae is characterized by the skeletonization of leaves. By feeding primarily on the leaf parenchyma while leaving the veins intact, the larvae strip the tree of its ability to photosynthesize effectively. Severe infestations can lead to partial or total defoliation, which stresses the tree and makes it susceptible to opportunistic diseases.

To protect trees from Alder sawfly infestations, consider the following control methods:

• Cultivating the soil beneath the host trees in autumn to disrupt overwintering pupae.
• Monitoring foliage for early signs of skeletonization and manually removing infected leaves if the infestation is localized.
• Applying systemic or contact insecticides during the larval stage if pest pressure exceeds economic thresholds.
• Encouraging natural predators such as parasitic wasps, which can help regulate population numbers.